The present invention relates to a method and an apparatus of controlling an automatic transmission system based on a manual transmission.
The automatic transmission systems based on the well-known manual transmission are provided with several shift gears arranged in the axial direction and a switching mechanism, such as a synchronous mechanism for switching the shift gears. The transmission system works while the switching mechanism is being automatically controlled with hydraulic pressure.
Such automatic transmission systems are better for power transfer efficiency than generally used automatic transmission systems having planetary gears and friction-engaged elements such as a clutch and a brake, as main components. Moreover, the automatic transmission systems are assembled with a small number of components, thus achieving lightweight structure and low production cost.
Japanese Un-Examined Patent Publication No. 63-2735 discloses a similar automatic transmission system with a sub-clutch provided at the input shaft of a transmission system for reducing shock during gearshifting. In detail, the sub-clutch is controlled by the hydraulic pressure while a main clutch is engaged which is installed between an engine crankshaft and the input shaft of the transmission system. The sub-clutch engagement control will reduce sudden reduction of output torque during upshifting to reduce the shock which occurs due to less acceleration.
Japanese Un-Examined Patent Publication No. 61-45163 and Japanese Patent Publication No. 2703169 also disclose such automatic transmission systems.
Japanese Un-Examined Patent Publication No. 61-261740 discloses gearshift control for controlling engagement of a sub-clutch during upshifting while controlling a throttle opening to temporarily lower engine output. In detail, torque of inertia will be generated due to variation in engine speed while the speed is being reduced after gearshifting. Therefore, the shock could easily occur when engine torque is constant because of abrupt increase in transfer torque of the sub-clutch due to generation of torque of inertia. The transfer torque of the sub-clutch is controlled so that it becomes constant while the engine speed is varying with sudden decrease in engine torque by an amount corresponding to generated torque of inertia.
A purpose of the present invention is to provide a method and an apparatus of controlling a transmission system that can effectively reduce shock.
The present invention provides an apparatus for controlling an automatic transmission having a switching mechanism for switching a plurality of shift gears, and a sub-clutch for transferring a torque from an input shaft to an output shaft, comprising: a first calculator to calculate an actual deceleration speed based on an engine speed; a second calculator to calculate a target deceleration speed by referring to an output torque generated during upshifting based on an engine torque; and a controller for controlling the transfer torque by feedback control such that an actual deceleration speed converges to the target deceleration speed.
Moreover, the present invention provides a transmission control method of controlling an automatic transmission having a switching mechanism for switching a plurality of shift gears and a sub-clutch for transferring a torque from an input shaft to an output shaft, comprising: calculating an actual deceleration speed based on an engine speed; calculating a target deceleration speed by referring to an output torque generated during upshifting based on an engine torque; and controlling the transfer torque by feedback control such that the actual deceleration speed converges the target deceleration speed.